We Here See In Two Distant
Countries A Similar Relation Between Plants And Insects Of The
Same Families, Though The Species Of Both Are Different.
When
man is the agent in introducing into a country a new species,
this relation is often broken:
As one instance of this I may
mention, that the leaves of the cabbages and lettuces, which
in England afford food to such a multitude of slugs and
caterpillars, in the gardens near Rio are untouched.
During our stay at Brazil I made a large collection of
insects. A few general observations on the comparative
importance of the different orders may be interesting to the
English entomologist. The large and brilliantly coloured
Lepidoptera bespeak the zone they inhabit, far more plainly
than any other race of animals. I allude only to the
butterflies; for the moths, contrary to what might have been
expected from the rankness of the vegetation, certainly
appeared in much fewer numbers than in our own temperate
regions. I was much surprised at the habits of Papilio
feronia. This butterfly is not uncommon, and generally
frequents the orange-groves. Although a high flier, yet
it very frequently alights on the trunks of trees. On these
occasions its head is invariably placed downwards; and its
wings are expanded in a horizontal plane, instead of being
folded vertically, as is commonly the case. This is the only
butterfly which I have ever seen, that uses its legs for running.
Not being aware of this fact, the insect, more than once, as I
cautiously approached with my forceps, shuffled on one side
just as the instrument was on the point of closing, and thus
escaped. But a far more singular fact is the power which
this species possesses of making a noise. [6] Several times when
a pair, probably male and female, were chasing each other
in an irregular course, they passed within a few yards of me;
and I distinctly heard a clicking noise, similar to that
produced by a toothed wheel passing under a spring catch. The
noise was continued at short intervals, and could be
distinguished at about twenty yards' distance: I am certain
there is no error in the observation.
I was disappointed in the general aspect of the Coleoptera.
The number of minute and obscurely coloured beetles
is exceedingly great. [7] The cabinets of Europe can, as yet,
boast only of the larger species from tropical climates. It
is sufficient to disturb the composure of an entomologist's
mind, to look forward to the future dimensions of a complete
catalogue. The carnivorous beetles, or Carabidae, appear
in extremely few numbers within the tropics: this is
the more remarkable when compared to the case of the
carnivorous quadrupeds, which are so abundant in hot
countries. I was struck with this observation both on entering
Brazil, and when I saw the many elegant and active forms
of the Harpalidae re-appearing on the temperate plains of
La Plata. Do the very numerous spiders and rapacious
Hymenoptera supply the place of the carnivorous beetles?
The carrion-feeders and Brachelytra are very uncommon;
on the other hand, the Rhyncophora and Chrysomelidae, all
of which depend on the vegetable world for subsistence, are
present in astonishing numbers.
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